PEERLESS Series MI Instruction manual

MI/MIH™
Boilers
Series
Gas
Installation,
Operation &
Maintenance
Manual

USING THIS MANUAL 1
A. INSTALLATION SEQUENCE . . . . . . . . . . . . .1
B. SPECIAL ATTENTION BOXES . . . . . . . . . . . .1
1. PREINSTALLATION 2
A. ACCESSIBILITY CLEARANCES . . . . . . . . . . .2
B. CLEARANCE FROM COMBUSTIBLE
CONSTRUCTION . . . . . . . . . . . . . . . . . . . . . .2
C. AIR FOR COMBUSTION AND
VENTILATION . . . . . . . . . . . . . . . . . . . . . . . . .2
D. INSTALLATION SURVEY . . . . . . . . . . . . . . . .5
E. PLANNING THE LAYOUT . . . . . . . . . . . . . . . .5
2. BOILER SET-UP 6
3. WATER PIPING AND CONTROLS 7
A. BOILER SUPPLY AND RETURN . . . . . . . . . . .7
B. SAFETY RELIEF VALVE . . . . . . . . . . . . . . . . .8
C. PIPING FOR ZONED SYSTEMS . . . . . . . . . .9
D. EXPANSION TANK . . . . . . . . . . . . . . . . . . . .10
E. INDIRECT-FIRED WATER HEATER . . . . . . .10
F. FREEZE PROTECTION . . . . . . . . . . . . . . . . .10
4. VENTING 11
A. INTEGRAL DRAFT HOOD . . . . . . . . . . . . . .11
B. VENT DAMPER INSTALLATION –
GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . .11
C. VENT PIPING AND CHIMNEY . . . . . . . . . . .12
D. BOILER REMOVAL FROM COMMON
VENTING SYSTEM . . . . . . . . . . . . . . . . . . .13
5. GAS PIPING 14
6. ELECTRICAL 16
A. WIRING . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
B. ZONED SYSTEM WIRING . . . . . . . . . . . . . .16
C. CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . .16
D. SEQUENCE OF OPERATION . . . . . . . . . . . .17
7. START-UP PROCEDURES 21
A. COMPLETING THE INSTALLATION . . . . . .21
B. CONTROL DESCRIPTIONS . . . . . . . . . . . . .25
C. ADJUSTMENT OF GAS PRESSURE
REGULATOR . . . . . . . . . . . . . . . . . . . . . . . . .25
D. ADJUSTMENT OF PILOT GAS FLOW . . . . .25
E. CHECKING BURNER INPUT . . . . . . . . . . . . .26
F. CHECK-OUT PROCEDURE . . . . . . . . . . . . . .26
8. TROUBLESHOOTING 28
A. SHUT-DOWN CAUSED BY PILOT OUTAGE,
BLOCKED VENT SHUT-OFF SWITCH OR
FLAME ROLL-OUT SAFETY SHUT-OFF
SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
B. TROUBLESHOOTING GUIDES . . . . . . . . . .28
9. MAINTENANCE 31
A. GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . .32
B. DAILY (WITH BOILER IN USE) . . . . . . . . . . .32
C. WEEKLY (WITH BOILER IN USE) . . . . . . . . .32
D. MONTHLY (WITH BOILER IN USE) . . . . . . .32
E. ANNUALLY (BEFORE START OF HEATING
SEASON) . . . . . . . . . . . . . . . . . . . . . . . . . . .33
10. BOILER DIMENSIONS & RATINGS 34
11. REPAIR PARTS 35
A. BASE/COMBUSTIBLE FLOOR PAN . . . . . . .35
B. MANIFOLD, GAS VALVE & PILOT . . . . . . . .36
C. BLOCK/DRAFT HOOD & JACKET . . . . . . . .38
D. CONTROLS/CIRCULATOR/VENT
DAMPER & CONVERSION KITS . . . . . . . . .40
TABLE OF CONTENTS
TABLE OF CONTENTS

1
A. INSTALLATION SEQUENCE
Follow the installation instructions provided in this
manual in the order shown. The order of these
instructions has been set in order to provide the installer
with a logical sequence of steps that will minimize
potential interferences and maximize safety during
boiler installation.
B. SPECIAL ATTENTION BOXES
Throughout this manual you will see special attention
boxes intended to supplement the instructions and make
special notice of potential hazards. These categories
mean, in the judgment of PB Heat, LLC.:
Indicates special attention is needed, but not directly
related to potential personal injury or property
damage.
NOTICE
Indicates a condition or hazard which will or can
cause minor personal injury or property damage.
CAUTION
DANGER
Indicates a condition or hazard which will cause
severe personal injury, death or major property
damage.
USING THIS MANUAL
USING THIS MANUAL
Indicates a condition or hazard which may cause
severe personal injury, death or major property
damage.
WARNING

2
A. ACCESSIBILITY CLEARANCES
Install boiler not less than 24″(610 mm) between the
left side, top, and front of the boiler and adjacent wall or
other appliance, when access is required for servicing.
B. CLEARANCE FROM COMBUSTIBLE
CONSTRUCTION
The design of this boiler is certified for alcove installation
with the following clearances:
1. 6″ (152 mm) between sides and combustible
construction.
2. 24″(610 mm) between top of jacket and
combustible construction.
3. 6″(152 mm) between draft hood and combustible
construction.
4. 6″(152 mm) between vent pipe and combustible
construction.
5. 10″(254 mm) between rear of jacket and
combustible construction.
C. AIR FOR COMBUSTION AND
VENTILATION
1. Adequate combustion air and ventilation air must be
provided for this appliance in accordance with the
section of the National Fuel Gas Code entitled, “Air
for Combustion and Ventilation” or applicable
provisions of the local building code. Subsections 2
through 8 as follows are based on the National Fuel
Gas Code requirements.
2. Required Combustion Air Volume: The total required
volume of indoor air is to be the sum of the required
volumes for all appliances located within the space.
Rooms communicating directly with the space in
which the appliances are installed and through
combustion air openings sized as indicated in
Subsection 3 are considered part of the required
volume. The required volume of indoor air is to be
determined by one of two methods.
a. Standard Method: The minimum required
volume of indoor air (room volume) shall be 50
cubic feet per 1000 BTU/Hr (4.8 m3/kW). This
method is to be used if the air infiltration rate is
unknown or if the rate of air infiltration is known
to be greater than 0.6 air changes per hour. As
an option, this method may be used if the air
infiltration rate is known to be between 0.6 and
0.4 air changes per hour. If the air infiltration rate
is known to be below 0.4 then the Known Air
Infiltration Rate Method must be used. If the
building in which this appliance is to be installed
is unusually tight, PB Heat recommends that the
air infiltration rate be determined.
b. Known Air Infiltration Rate Method: Where
the air infiltration rate of a structure is known,
the minimum required volume of indoor air for
appliances other than fan assisted and for the
Series MI™Boiler shall be determined as follows:
PREINSTALLATION
1. PREINSTALLATION
Read carefully, study these instructions before beginning work.
This boiler must be installed by a qualified contractor.
The boiler warranty can be voided if the boiler is not installed, maintained and serviced correctly.
The equipment must be installed in accordance with those installation requirements of the authority having
jurisdiction or, in the absence of such requirements, to the current edition of the
National Fuel Gas Code , ANSI
Z223.1/NFPA 54 and/or CAN/CSA B149.1,
Natural Gas and Propane Installation Code .
Where required by the authority having jurisdiction, the installation must conform to
American Society of
Mechanical Engineers Safety Code for Controls and Safety Devices for Automatically Fired Boilers,
ASME CSD-1.
NOTICE
Do not install this boiler on carpeting. Boiler
installation on carpeting is a fire hazard. Install this
boiler on non-combustible flooring or use a
combustible floor pan to install this boiler on other
non-carpeted flooring.
WARNING
Do not install this boiler on combustible flooring
unless it is installed on a special combustible floor
pan provided by PB Heat, LLC. Boiler installation on
combustible flooring without the special pan is a fire
hazard.
To order combustible floor pan, use the 5-digit stock
codes listed in Table 11.1 of this manual.
WARNING
21 ft3Iother
ACH 1000Btu/hr
Required Volumeother =
⎛
⎜
⎝
⎛
⎜
⎝

3
where:
Iother = Input of appliances other than fan
assisted in Btu/hr
ACH = air change per hour (percent of the
volume of the space exchanged per
hour, expressed as a decimal)
For fan assisted appliances, calculate the required
volume of air using the following equation:
Ifan = Input of the fan assisted appliances in
Btu/hr
Note: These calculations are not to be used for
infiltration rates greater than 0.60 ACH.
3. Indoor Air Opening Size and Location: Openings
connecting indoor spaces shall be sized and located
as follows:
a. Combining spaces on the same floor:
Provide two permanent openings communicating
with additional spaces that have a minimum free
area of 1 in2per 1000 Btu/hr (22 cm2per 1000 W)
of the total input rating of all gas fired equipment
but not less than 100 in2(645 cm2). One
opening is to begin within 12 inches (305 mm)
from the top of the space and the other is to
begin within 12 inches (305 mm) from the floor.
The minimum dimension of either of these
openings shall be 3 inches (76 mm). See Figure
1.1 for an illustration of this arrangement.
b. Combining spaces on different floors:
Provide one or more permanent openings
communicating with additional spaces that have
a total minimum free area of 2 in2per 1000
Btu/hr (44 cm2per 1000 W) of total input rating
of all equipment. See Figure 1.2 for an
illustration of this arrangement.
4. Outdoor Combustion Air: Outdoor combustion air is
to be provided through one or two permanent
openings. The minimum dimension of these air
openings is 3 inches (76 mm).
a. Two Permanent Opening Method: Provide
two permanent openings. One opening is to
begin within 12 inches (305 mm) of the top of
the space and the other is to begin within 12
inches (305 mm) of the floor. The openings are
to communicate directly or by ducts with the
outdoors or with spaces that freely communicate
with the outdoors. The size of the openings shall
be determined as follows:
i. Where communicating directly or through
vertical ducts with the outdoors each opening
shall have a minimum free area of 1 in2per
4000 Btu/hr (22 cm2per 4000 W) of total
input rating for all equipment in the space.
See Figure 1.3 for openings directly
communicating with the outdoors or Figure
1.4 for openings connected by ducts to the
outdoors.
PREINSTALLATION
15 ft3Ifan
ACH 1000Btu/hr
Required Volumefan =⎛
⎜
⎝
⎛
⎜
⎝
Figure 1.1: Air Openings – All Air from Indoors
on the Same Floor
Figure 1.2: Air Openings – All Air from Indoors
on Different Floors
Figure 1.3: Air Openings – All Air Directly from
Outdoors

4
ii. Where communicating with the outdoors
through horizontal ducts, each opening shall
have a minimum free area of 1 in2per 2000
Btu/hr (22 cm2per 2000 W) of total rated
input for all appliances in the space. See
Figure 1.5.
b. One Permanent Opening Method: Provide
one permanent opening beginning within 12
inches (305 mm) of the top of the space. The
opening shall communicate directly with the
outdoors, communicate through a vertical or
horizontal duct, or communicate with a space
that freely communicates with the outdoors. The
opening shall have a minimum free area of 1 in2
per 3000 Btu/hr of total rated input for all
appliances in the space and not less than the
sum of the cross-sectional areas of all vent
connectors in the space. The gas-fired equipment
shall have clearances of at least 1 inch (25 mm)
from the sides and back and 6 inches (150 mm)
from the front of the appliance. See Figure 1.6
for this arrangement.
5. Combination Indoor and Outdoor Combustion Air:
If the required volume of indoor air exceeds the
available indoor air volume, outdoor air openings or
ducts may be used to supplement the available
indoor air provided:
a. The size and location of the indoor openings
comply with Subsection 3.
b. The outdoor openings are to be located in
accordance with Subsection 4.
c. The size of the outdoor openings are to be sized
as follows:
where:
Areq = minimum area of outdoor openings.
Afull = full size of outdoor openings calculated
in accordance with Subsection 4.
Vavail = available indoor air volume
Vreq = required indoor air volume
6. Engineered Installations: Engineered combustion air
installations shall provide an adequate supply of
combustion, ventilation, and dilution air and shall be
approved by the authority having jurisdiction.
7. Mechanical Combustion Air Supply:
a. In installations where all combustion air is
provided by a mechanical air supply system, the
combustion air shall be supplied from the
outdoors at the minimum rate of 0.35 ft3/min per
1000 Btu/hr (0.034 m3/min per 1000 W) of the
total rated input of all appliances in the space.
b. In installations where exhaust fans are installed,
additional air shall be provided to replace the
exhaust air.
PREINSTALLATION
Figure 1.4: Air Openings – All Air from Outdoors
through Vertical Ducts
Figure 1.5: Air Openings – All Air from Outdoors
through Horizontal Ducts
Figure 1.6: Air Openings – All Air from Outdoors
through One Opening
Vavail
1 – Vreq
Areq = Afull x⎛
⎜
⎝
⎛
⎜
⎝

5
c. Each of the appliances served shall be
interlocked to the mechanical air supply to
prevent main burner operation when the
mechanical air supply system is not in operation.
d. In buildings where the combustion air is provided
by the mechanical ventilation system, the system
shall provide the specified combustion air rate in
addition to the required ventilation air.
8. Louvers & Grills:
a. The required size of openings for combustion,
ventilation, and dilution air shall be based on the
net free area of each opening.
i. Where the free area through a louver or grille
is known, it shall be used in calculating the
opening size required to provide the free area
specified.
ii. Where the free area through a louver or grille
is not known, it shall be assumed that wooden
louvers will have 25% free area and metal
louvers and grilles will have 75% free area.
iii. Nonmotorized dampers shall be fixed in the
open position.
b. Motorized dampers shall be interlocked with the
equipment so that they are proven in the full
open position prior to ignition and during
operation of the main burner.
i. The interlock shall prevent the main burner
from igniting if the damper fails to open
during burner startup.
ii. The interlock shall shut down the burner if
the damper closes during burner operation.
9. Combustion Air Ducts
a. Ducts shall be constructed of galvanized steel or
an equivalent corrosion- resistant material.
b. Ducts shall terminate in an unobstructed space,
allowing free movement of combustion air to the
appliances.
c. Ducts shall serve a single space.
d. Ducts shall not serve both upper and lower
combustion air openings where both such
openings are used. The separation between ducts
serving upper and lower combustion air
openings shall be maintained to the source of
combustion air.
e. Ducts shall not be screened where terminating in
an attic space.
f. Horizontal upper combustion air ducts shall not
slope downward toward the source of the
combustion air.
g. The remaining space surrounding a chimney
liner, gas vent, special gas vent, or plastic piping
installed within a masonry, metal, or factory built
chimney shall not be used to supply combustion
air.
h. Combustion air intake openings located on the
exterior of buildings shall have the lowest side of
the combustion air intake opening at least 12
inches (305 mm) above grade.
D. INSTALLATION SURVEY
For new and existing installations, a Water Installation
Survey is available from PB Heat, LLC. The survey will
provide information on how a hot water boiler works
with your specific system and will provide an overview
of hot water system operation in general.
You can also use this survey to locate system problems
which will have to be corrected. To obtain copies of the
Water Installation Survey, contact your PB Heat
representative or download it from PeerlessBoilers.com.
E. PLANNING THE LAYOUT
Prepare sketches and notes of the layout to minimize the
possibility of interferences with new or existing
equipment, piping, venting and wiring.
Liquefied Petroleum (LP) is heavier than air and may
collect or “pool” in a low area in the event of a leak
from defective equipment. This gas may then ignite,
resulting in a fire or explosion.
WARNING
PREINSTALLATION

6
BOILER SET-UP
1. Provide a sound, level foundation. Locate boiler as
near to the chimney or outside wall as possible and
centralized with respect to the heating system.
2. Locate boiler in front of installation position before
removing crate.
3. If using combustible floor pan, position pan on
foundation or flooring.
4. Separate the wood shipping pallet from the boiler
base by removing two (2) hold-down bolts at each
end of the boiler base.
5. Move boiler into final position. If using combustible
floor pan, install boiler on pan as outlined in the
instructions included with the pan.
2. BOILER SET-UP

7
A. BOILER SUPPLY AND RETURN
1. Size the supply and return to suit the system. A
typical piping arrangement is shown in Figure 3.1.
Refer also to the I=B=R Guide - Residential
Hydronic Heating Installation/Design and the PB
Heat Water Survey for additional guidance during
water piping installation.
2. Return Piping:
Pipe the drain valve to a tee, provided, and the
1-1/4 NPT return tapping near the bottom of the left
section. Pipe the return to the tee. Pipe the drain
valve nipples and tee to the 1-1/4 NPT return
tapping as shown in Figure 3.1.
3. Supply Piping:
Pipe the supply to the 1-1/2 NPT supply tapping at
the top and rear of the boiler.
4. When system return water temperature will be below
130°F (54°C), pipe the boiler with a bypass
arrangement to blend the system return and hot
supply to obtain at least 130°F (54°C) entering the
boiler. For more information on bypass piping,
consult the PB Heat Water Survey.
3. WATER PIPING AND CONTROLS
Figure 3.1: Supply and Return Piping
WATER PIPING AND CONTROLS

8
6. Install this boiler so that the gas ignition system
components are protected from water (dripping,
spraying, etc.) during appliance operation and
service (circulator replacement, condensate trap,
control replacements, etc.).
7. If this boiler and distribution system is used in
conjunction with a refrigeration system, pipe the
chilled medium in parallel with the boiler and install
the proper valve to prevent the chilled medium from
entering the boiler. A drawing illustrating this hook-
up is provided in Figure 3.2.
8. When the boiler is connected to heating coils
located in air handling units where they may be
exposed to refrigerated air circulation, install flow
control valves or other automatic means to prevent
gravity circulation of the boiler water during the
cooling cycle.
9. If this boiler is installed above radiation level,
provide a low water cutoff device, either as a part of
the boiler or at the time of boiler installation.
B. SAFETY RELIEF VALVE
1. Locate safety relief valve and fittings in bag
assembly.
2. If air elimination is not required at the safety relief
valve tapping, install valve and piping as shown in
Figure 3.3.
3. For air elimination at the safety relief valve tapping,
install valve and piping as shown in Figure 3.4.
Pipe the discharge of safety relief valve to prevent
injury in the event of pressure relief. Pipe the
discharge to a drain. Provide piping that is the same
size as the safety relief valve outlet.
CAUTION
Figure 3.4: Safety Relief Valve Hook-Up with
Air Elimination
Figure 3.3: Safety Relief Valve Hook-Up
Installation with Air Elimination in
System Piping
Figure 3.2: Parallel Hook-Up with Water Chiller
WATER PIPING AND CONTROLS

9
C. PIPING FOR ZONED SYSTEMS
1. See Figures 3.5 and 3.6 for basic zoned system
layouts.
2. Run each zone pipe down then up to zone to
prevent air accumulation in piping.
3. If required, provide means to isolate and drain each
zone separately.
WATER PIPING AND CONTROLS
Figure 3.5: Zone Piping with Zone Valves
Figure 3.6: Zone Piping with Circulators

10
D. EXPANSION TANK
1. Consult the tank manufacturer’s instructions for
specific information relating to tank installation. Size
the expansion tank for the required system volume
and capacity. See Table 10.2 in Section 10 for boiler
water content.
2. Expansion tanks are available with built-in fill valves
and check valves for reducing supply water pressure
and maintaining minimum system pressure. Check
the design features of the tank and provide valves as
necessary. Refer back to Figure 3.1 for typical
expansion tank piping.
E. INDIRECT-FIRED WATER HEATER
If the boiler is to be used in conjunction with an indirect-
fired water heater, refer to Figure 3.7 for typical piping.
Follow the instructions provided by the water heater
manufacturer. Pipe the water heater as a separate zone.
F. FREEZE PROTECTION
For new or existing systems that must be freeze-
protected:
1. Glycol in hydronic applications is specially
formulated for this purpose. It includes inhibitors
which prevent the glycol from attacking metallic
system components. Make certain that the system
fluid is checked for the correct glycol concentration
and inhibitor level.
2. The glycol solution should be tested at least once a
year and as recommended by the glycol
manufacturer.
3. Glycol solutions expand more than water. For
example, a 50% by volume solution expands 4.8%
in volume for a temperature increase from 32°F
(0°C) to 180°F (82°C), while water expands 3% with
the same temperature rise. Allowance must be made
for this expansion in system design.
4. For more information, consult the PB Heat Water
Installation Survey and the glycol manufacturer.
WATER PIPING AND CONTROLS
Use only inhibited propylene glycol solutions of up to
50% by volume with water. Ethylene glycol is toxic
and can attack gaskets and seals used in hydronic
systems.
WARNING
Figure 3.7: Typical Piping with Indirect-Fired Water Heater

11
A. INTEGRAL DRAFT HOOD
1. The MI/MIH™boiler is equipped with a built-in draft
hood. This device is designed to:
a. provide for the ready escape of flue gases from
the boiler in the event of no draft.
b. prevent a backdraft from entering the boiler.
c. control stack draft during operation.
These tasks are accomplished without the extra
height requirements of a separate draft hood.
2. The draft hood relief opening is the large rectangular
passage at the front of the boiler. Make certain that
there are no obstructions to airflow in front of this
opening.
3. A vent safety shut-off switch is located within the
draft relief opening to shut off the boiler in case of a
blocked vent condition. See Section 7B for details
regarding this device. See Figure 6.1 in Section 6
(Electrical) for spill switch location.
4. The vent damper can be mounted directly onto the
round draft hood outlet (vent connector) on top of
the boiler, or in vent piping close to the boiler. See
the Vent Damper Installation Instructions below.
B. VENT DAMPER INSTALLATION –
GENERAL
1. Do not use one vent damper to control two or more
heating appliances. See Figure 4.1.
2. Follow these and the installation instructions that are
included with the vent damper. Observe the cautions
and warnings that accompany all instructions.
3. Make certain that minimum clearances provided in
the vent damper manufacturer’s instructions are
maintained and that adequate space is available for
damper access and service.
4. Orient the damper operator to facilitate connection
of the harness with the vent damper and boiler. Note
flue gas flow arrow on vent damper and orient as
required. For installation with damper mounted in
vertical position, see Figure 4.2. For installation with
damper mounted in horizontal position, mount the
unit as shown in Figure 4.3 to avoid excessive heat
on the operator or condensation drips into the
operator.
4. VENTING
Figure 4.1: Venting Multiple Appliances
VENTING

12
Figure 4.2: Venting with Vent Damper in Vertical Position
Figure 4.3: Venting with Vent Damper in Horizontal Position
C. VENT PIPING AND CHIMNEY
1. Install vent piping in accordance with Venting of
Equipment part of the National Fuel Gas Code, ANSI
Z223.1/NFPA 54, sections 7.2, 7.3 or 7.4 of
CAN/CSA B149.1, Natural Gas and Propane
Installation Code, or applicable provisions of the
local building codes.
2. Inspect the existing chimney and lining for structural
soundness, corrosion and perforations. Repair as
necessary.
3. Install vent pipe to slope upward at least 1/4” per
lineal foot (21 mm per meter) between the draft
hood outlet and the chimney.
4. Before connection of joints, inspect the vent pipe
interior for foreign objects such as tools, equipment,
rags, etc. and remove if present.
5. Insert vent pipe into but not beyond the inside wall
of the chimney flue.
6. Do not connect vent connectors serving appliances
vented by natural draft into any portion of
mechanical draft systems operating under positive
pressure.
7. Support horizontal portions of the venting system to
prevent sagging by use of metal strapping or
equivalent means. Locate supports at no more than
4 foot (1.2 meter) intervals.
VENTING

D. BOILER REMOVAL FROM COMMON
VENTING SYSTEM
At the time of removal of an existing boiler, follow these
steps with each appliance remaining connected to the
common venting system placed in operation, while the
other appliances remaining connected to the common
venting system are not in operation:
a. Seal any unused openings in the common venting
system.
b. Visually inspect the venting system for proper size
and horizontal pitch and determine there is no
blockage or restriction, leakage, corrosion and other
deficiencies which could cause an unsafe condition.
c. Insofar as is practical, close all building doors and
windows and all doors between the space in which
the appliances remaining connected to the common
venting system are located and other spaces of the
building. Turn on any clothes dryers and any
appliance not connected to common venting system.
Turn on any exhaust fans, such as range hoods and
bathroom exhausts, so they will operate at maximum
speed. Do not operate a summer exhaust fan. Close
fireplace dampers.
d. Place in operation the appliance being inspected.
Follow the lighting instructions. Adjust thermostat so
appliance will operate continuously.
e. Test for spillage at the draft hood relief opening after
5 minutes of main burner operation. Use the flame
of a match or candle, or smoke from a cigarette,
cigar, or pipe.
f. After it has been determined that each appliance
remaining connected to the common venting system
properly vents when tested as outlined above, return
doors, windows, exhaust fans, fireplace dampers and
any other gas-burning appliance to their previous
conditions of use.
g. Any improper operation of the common venting
system should be corrected so that the installation
conforms with the current edition of the National
Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or
CAN/CSA B149.1, Natural Gas and Propane
Installation Code. When resizing any portion of the
common venting system, the common venting
system should be resized to approach the minimum
size as determined using the appropriate tables in
the National Fuel Gas Code, ANSI Z223.1/NFPA 54
and/or CAN/CSA B149.1, Natural Gas and Propane
Installation Code.
13
VENTING

14
1. Size and install the gas supply piping properly in
order to provide a supply of gas sufficient to meet
the maximum demand without undue loss of
pressure between the meter and the boiler.
2. Determine the volume of gas to be provided to the
boiler in cubic feet per hour. To obtain this value,
divide the Btu per hour rating (on the boiler rating
plate) by the heating value of the gas in Btu per
cubic feet. Obtain the heating value of the gas from
the gas supplier. As an alternative, use Table 5.1, 5.2
or 5.3 on the next page to obtain the volume of gas
to be provided to the boiler.
3. Use the value obtained above as the basis for piping
sizing. Size the gas piping in accordance with Table
5.4. Consult the National Fuel Gas Code ANSI
Z223.1/NFPA 54 and/or CAN/CSA B149.1, Natural
Gas and Propane Installation Code for proper sizing
options.
4. Locate the drop pipe adjacent to, but not in front of
the boiler.
5. Install a sediment trap. See Figure 5.1. Locate a tee
in the drop pipe at same elevation as the gas inlet
connection to the boiler. Extend the drop pipe to a
pipe cap.
6. Install a ground joint union ahead of the gas control
assembly to permit servicing of the control. Some
local codes require an additional service valve when
using the combination gas controls. If your code
requires such a valve, a suggested location is shown
in Figure 5.1.
7. Check piping for leaks.
Use an approved gas detector, a non-corrosive leak
detection fluid or other leak detection method. If
leaks are found, turn off all gas flow and repair as
necessary.
8. Disconnect the boiler and its individual shut-off valve
from the gas supply piping system during any
pressure testing of that system at test pressure in
excess of 1/2 psig (3.5 kPa).
Isolate the boiler from the gas supply piping system
by closing its individual service valve during any
pressure testing of the gas supply piping system at
test pressure equal to or less than 1/2 psig (3.5 kPa).
9. Minimum permissible supply pressure for purposes of
input adjustment:
MI-09 Standing Pilot
Natural Gas 5.2″ WC (1.3 kPa)
All other MI/MIH™
Natural Gas 5.0″ WC (1.2 kPa)
All MI™LP Gas 11.0″ WC (2.7 kPa)
Maximum permissible supply pressure to the boiler:
All MI/MIH™Natural Gas 13.5″ WC (3.5 kPa)
All MI™LP Gas 13.5″ WC (3.5 kPa)
5. GAS PIPING
Figure 5.1: Gas Connection to Boiler
When checking for leaks, do not use matches,
candles, open flames or other methods that provide a
source of ignition. This can ignite a gas leak,
resulting in fire or explosion.
WARNING
Use a pipe joint sealing compound that is resistant to
the action of liquefied petroleum gas. A non-resistant
compound may lose sealing ability in the presence of
this gas, resulting in a gas leak and fire or explosion
potential.
WARNING
Do not subject the gas valve to more than 1/2 psi (3.5
kPa) pressure. Doing so may damage the valve.
CAUTION
GAS PIPING

15
Table 5.4: Pipe Capacity
Capacity of pipe of different diameters and lengths in cubic feet
per hour [cubic meter per hour] with a pressure drop of 0.3
inches of water (75 Pa) and specific gravity of 0.60. No
allowance for an ordinary number of fittings is required.
Table 5.1: MI™Boiler – Natural Gas
Table 5.2: MI™Boiler – LP Gas
Table 5.3: MIH™Boiler – Natural Gas
GAS PIPING
Model Input
Cubic Feet / Hour Cubic Meters / Hour
MI-03 70 2.0
MI-04 105 3.0
MI-05 140 4.0
MI-06 175 5.0
MI-07 195 5.5
MI-08 227.5 6.4
MI-09 260 7.4
Model Input
Cubic Feet / Hour Cubic Meters / Hour
MI-03 28 0.8
MI-04 42 1.2
MI-05 56 1.6
MI-06 70 2.0
MI-07 78 2.2
MI-08 91 2.6
MI-09 104 2.9
Pipe
Length in
Feet
[Meters]
3/4"
Pipe
1"
Pipe
1-1/4"
Pipe
1-1/2"
Pipe
10 [3.0] 278 [7.9] 520 [14.7] 1050 [29.7] 1600 [45.3]
20 [6.1] 190 [5.4] 350 [9.9] 730 [20.7] 1100 [31.1]
30 [9.1] 152 [4.3] 285 [8.1] 590 [16.7] 890 [25.2]
40 [12.2] 130 [3.7] 245 [6.9] 500 [14.2] 760 [21.5]
50 [15.2] 115 [3.3] 215 [6.1] 440 [12.5] 670 [19.0]
60 [18.3] 105 [3.0] 195 [5.5] 400 [11.3] 610 [17.3]
Maximum Capacity Correction Factors for
Specific Gravity other than 0.60.
Model Input
Cubic Feet / Hour Cubic Meters / Hour
MIH-03 65 1.8
MIH-04 97.5 2.8
MIH-05 130 3.7
MIH-06 162.5 4.6
Specific Gravity 0.50 0.55 0.60 0.65 0.70 0.75
Correction Factor 1.10 1.04 1.00 0.96 0.93 0.90
Specific Gravity 0.80 0.85 0.90 1.00 1.10 1.20
Correction Factor 0.87 0.84 0.82 0.78 0.74 0.71
Specific Gravity 1.30 1.40 1.50 1.60 1.70 1.80
Correction Factor 0.68 0.66 0.63 0.61 0.59 0.58

A. WIRING
1. See Figure 6.1 for location of wiring and controls.
Use Figures 6.2 and 6.3 to connect the boiler to a
power supply and to connect components to the
boiler.
2. Connect the boiler by a separate, permanently live
electrical supply line with a fused switch.
3. Connect the vent damper harness to the damper
motor as shown in Figure 6.1.
4. Adjust the thermostat heat anticipator to 0.2 Amp.
B. ZONED SYSTEM WIRING
See Figure 6.5 for typical wiring with zone valves. See
Figure 6.6 for typical wiring with zone circulators. When
wiring a zoned heating system, follow all applicable
codes, ordinances and regulations.
C. CONTROLS
1. For proper location of controls and accessories refer
to Figure 6.1 and Section 11.
2. See the attached control sheets for specific details
regarding the installation of the various controls.
3. This boiler is supplied with safety devices in addition
to the limit. For a description of these devices and
how they work to ensure the safe operation of the
boiler, see Section 7B.
4. If the circulator is mounted in the supply piping,
provide longer wiring harness as required.
ELECTRICAL
6. ELECTRICAL
This unit when installed must be electrically grounded in accordance with the requirements of the authority
having jurisdiction or, in the absence of such requirements, with the current edition of the
National Electrical
Code
, ANSI/NFPA 70 and/or the Canadian Electrical Code , Part 1 CSA C22.1, Electrical Code.
NOTICE
Figure 6.1: Wiring, Controls and Safety Devices
Install all electrical wiring in accordance with the National Electrical Code and local requirements.
Do not power zone valves directly from the boiler
limit. Doing so will greatly reduce the life of the
transformer. Use a separate transformer sized to
handle the total of all zone valve electrical loads.
NOTICE
16

17
D. SEQUENCE OF OPERATION
1. Standing Pilot (See Figure 6.2 above)
a. The vent damper is continuously powered. On a
call for heat, limit relay R is energized, which
energizes:
●the circulator (when used) through contact
R1, and
●the vent damper operator through contact R2,
provided that the high-limit switch is
closed.
The vent damper operator opens the damper.
b. Once the damper is proven open, the gas valve
energizes, provided that all of the following
conditions are met:
●the pilot thermocouple is proving flame
●the blocked vent switch is closed, and
●the flame rollout switch is closed.
Pilot flame is monitored through the pilot
thermocouple. If pilot flame is lost during a call
for heat, main and pilot gas flow will be shut off.
The valve must then be manually reset by
following the Lighting Instructions mounted on
the jacket panel and included in Section 7 of this
manual.
c. When the call for heat ends:
●Limit relay R de-energizes, which opens
contacts R1 and R2.
●The circulator shuts down.
●The gas valve de-energizes.
●The vent damper closes.
d. If temperature exceeds limit setting, main burners
shut off and circulator continues to operate.
ELECTRICAL
Figure 6.2: Wiring and Connection Diagram – Standing Pilot (Continuous Ignition)

18
ELECTRICAL
2. Intermittent Ignition (see Figure 6.3 above)
a. The vent damper is continuously powered. On a
call for heat, limit relay R is energized, which
energizes:
●the circulator (when used) through contact
R1, and
●the vent damper operator through contact R2,
provided that the high-limit aquastat switch is
closed.
The damper operator opens the vent damper.
b. Once the damper is proven open, the ignition
circuit within the gas valve energizes, provided
that all of the following conditions are met:
●the blocked vent switch is closed, and
●the flame rollout switch is closed.
c. When the call for heat ends:
●Limit relay R de-energizes, which opens
contacts R1 and R2.
●The circulator shuts down.
●The gas valve de-energizes.
●The vent damper closes.
d. If temperature exceeds limit setting, main burners
shut off and circulator continues to operate.
Figure 6.3: Wiring and Connection Diagram – Intermittent Ignition